Compositions and processes for immersion lithography

ABSTRACT

The present invention relates to barrier layer compositions that are applied above a photoresist composition for immersion lithography processing. In a further aspect, new methods are provided for immersion lithography processing.

The present application claims the benefit of provisional applicationNo. 60/585,119, filed Jul. 2, 2004, which is incorporated herein byreference in its entirety.

The present invention relates to barrier layer compositions that areapplied above a photoresist composition for immersion lithographyprocessing. In a further aspect, new methods are provided for immersionlithography processing.

Photoresists are photosensitive films used for transfer of an image to asubstrate. A coating layer of a photoresist is formed on a substrate andthe photoresist layer is then exposed through a photomask to a source ofactivating radiation. The photomask has areas that are opaque toactivating radiation and other areas that are transparent to activatingradiation. Exposure to activating radiation provides a photoinducedchemical transformation of the photoresist coating to thereby transferthe pattern of the photomask to the photoresist coated substrate.Following exposure, the photoresist is developed to provide a reliefimage that permits selective processing of a substrate.

The growth of the semiconductor industry is driven by Moore's law whichstates that the complexity of an IC device doubles on average every twoyears. This necessitates the need to lithographically transfer patternsand structures with ever decreasing feature size.

One approach to achieving smaller feature sizes is to use shorterwavelengths of light, however, the difficulty in finding materials thatare transparent below 193 nm has led to the option of using immersionlithography to increase the numerical aperture of the lens by simplyusing a liquid to focus more light into the film. Immersion lithographyemploys a relatively high refractive index fluid between the lastsurface of an imaging device (e.g., KrF or ArF stepper) and the firstsurface on a wafer or other substrate.

Immersion microscopy has reported as a method for increasing thenumerical aperture of a lens by using a liquid with an index ofrefraction greater than air. The improvement can be quantified and theminimum line width, W, is calculated as follows:W=k ₁ λ/NA  Eq.1where k₁ is the resolution factor, k is the wavelength of light and NAis the numerical aperture.

For air which has an index of refraction of 1, the practical limit ofthe numerical aperture is 0.93. For materials with index greater than 1,NA greater than 1 are achievable based on the following formula:NA=n sin(α)=d/(2f)  Eq.2substituting for NA it is the equation can be simplified as shown below:W=k ₁ λ/nsin(α)  Eq.3

where n is the index of refraction of the immersion fluid and α is theacceptance angle of the lens. Thus for water which has an index ofrefraction of 1.47, a line width at 193 nm of 35 nm is possible.

Currently, extensive and proven immersion lithography systems do not yetexist.

See, for instance, Chemical and Engineering News, pages 18-24 (Jun. 28,2004).

Reliable and convenient photoresist and imaging processes for immersionlithography are clearly needed.

It would be desirable to new materials and processes for immersionphotolithograpy.

We now provide new compositions and processes for immersionphotolithography.

More particularly, in a first aspect, we provide new overcoating (topcoat or barrier layer) compositions that are applied above a photoresistcomposition layer and preferably can at least inhibit migration ofcomponents of the photoresist layer into a fluid (e.g. water) employedin an immersion lithography process.

Preferred barrier layers of the invention include those that contain oneor more non-solvent carrier materials (components) such as one or moreresins that do not contain fluorine substitution at least in the resinbackbone.

Barrier compositions of the invention may comprise a variety ofmaterials and preferred barrier composition components are highermolecular weight materials such as materials having a molecular weightin excess of about 500, 1000, 1500 or 2000 daltons. Preferred barriercomposition materials also include those that are substantiallylithographically inert, i.e. materials that do not undergo bond-breakingreactions during typical lithographic processing steps of pre-exposureand post-exposure thermal treatments, imaging, or otherwise react withimmersion fluid.

Preferred barrier composition materials include resins that contain Siand/or hetero atom (particularly N, O or S, especially O or S)substitution. Additional preferred barrier composition materials maycomprise zirconia and/or hafnia, which can be useful to provide acomposition of increased refractive index. Preferred barrier compositionmaterials also will be substantially free of aromatic groups (e.g., lessthan about 5, 4, 3, 2, or 1 weight percent of total composition beingaromatic groups) such as phenyl, naphthyl or anthracenyl to avoidexcessive absorbance of exposure radiation such as sub-300 nm exposureradiation (e.g. 248 nm) or sub-200 nm radiation (e.g. 193 nm). Aliphaticpolymers (i.e. polymers that have essentially or completely no aromaticcontent) are preferred, including those that comprise carbonate, ester,ether, hydroxy or other polar group substitution. Particularly preferredbarrier layers for use in an immersion lithography process includeresins that comprise Si atoms, such as one or more organopolysilciamaterials particularly one or more silsesquioxane or siloxane resins.

Particularly preferred barrier compositions of the invention can atleast inhibit migration of one or more components from an underlyingphotoresist composition layer into the immersion fluid (e.g. water orsome type of aqueous composition) positioned between the exposure tooland the barrier composition layer. As should be understood, the term“immersion fluid” as referred to herein means a fluid (e.g. water)interposed between an exposure tool and a photoresist coated substrateto conduct immersion lithography.

We have found that migration of acid from a photoresist layer into theimmersion fluid layer can be particularly problematic. Among otherthings, the acid or other photoresist materials that migrate into theimmersion fluid can damage the exposure tool as well as reduceresolution of an image patterned into a photoresist layer.

As referred to herein, a barrier layer will be considered as inhibitingthe migration of photoresist material into immersion fluid if adecreased amount of acid or organic material is detected in theimmersion fluid upon use of the barrier composition relative to the samephotoresist system that is processed into the same manner, but in theabsence of the barrier composition layer. Detection of photoresistmaterial in the immersion fluid can be conducted as described in Example8 which follows and includes mass spectroscopy analysis of the immersionfluid before exposure to the photoresist (with and without theovercoated barrier composition layer0 and then after lithographicprocessing of the photoresist layer with exposure through the immersionfluid. Preferably, the barrier composition provides at least a 10percent reduction in photoresist material (again, acid or organics asdetected by mass spectroscopy) residing in the immersion fluid relativeto the same photoresist that does not employ any barrier layer (i.e.immersion fluid directly contacts the photoresist layer), morepreferably the barrier composition provides at least a 20, 50, or 100percent reduction photoresist material (again, acid or organics)residing in to the immersion fluid relative to the same photoresist thatdoes not employ any barrier layer.

In a further aspect, the invention provides new methods for lithographicprocessing in an immersion exposure protocol. Preferred methods of theinvention may include the following steps:

1) apply a photoresist composition (e.g. by spin coating) to a substratesuch as a semiconductor wafer. The photoresist may be suitably appliedon the wafer surface or a material previously applied over the wafersuch as an organic or inorganic antireflective composition, or aplanarizing layer, and the like;

2) optionally thermally treat the applied photoresist composition toremove solvent carrier, e.g. at about 120° C. or less for about 30 to 60seconds. In preferred aspects of the invention, however, the photoresistcomposition solvent carrier is not removed by thermal treatment prior toapplying a barrier composition;

3) above the photoresist composition, apply a barrier composition of theinvention, e.g. by spin coating. The coated substrate then may bethermally treated to remove solvent carrier of the barrier compositionand preferably as discussed the photoresist composition, if that solventhas not already been removed;

4) exposing the overcoated photoresist layer to patterned activatingradiation with a fluid (e.g. a fluid comprising water) interposedbetween the exposure tool and the coated substrate, i.e. immersionexposing the photoresist layer by a fluid layer interposed between theexposure tool and the barrier composition layer. The interposed fluidtypically contacts the barrier composition.

In yet another aspect, the invention provides further methods forlithographic processing in an immersion exposure protocol, whereundesired migration or other transfer of photoresist compositioncomponent(s) can be reduced. These methods in general include atreatment or washing of a photoresist composition layer with a solventcomposition (aqueous or non-aqueous). If desired, a barrier compositionlayer may be applied over the photoresist composition layer that hasbeen treated with the solvent composition, but use of a barriercomposition layer is not required.

Such a solvent composition treatment step can remove photoresistcomposition materials that can migrate into the immersion fluid duringsubsequent exposure.

In such methods, suitably a solvent composition is applied such as byspin coating to a photoresist composition layer. The photoresistcomposition layer optionally may have solvent carrier removed such as bythermal treatment prior to the solvent composition treatment step. Thesolvent treatment composition may be an aqueous composition (e.g. wateror water/organic mixture) or a non-aqueous component and comprise one ormore organic solvents, preferably one or more polar solvents such as oneor more alcohols such as isopropanol and the like. A water/isopropanolsolvent mixture for the treatment step also is preferred. The solventcomposition then may be substantially removed such as by furtherspinning and the barrier composition applied over the photoresistcomposition layer. As mentioned, if desired, a barrier composition maybe applied such as by spin coating over the solvent composition-treatedphotoresist composition layer.

Preferred imaging wavelengths of lithographic systems of the inventioninclude sub-300 nm wavelengths e.g. 248 nm, and sub-200 nm wavelengthse.g. 193 nm. Particularly preferred photoresists for use in systems ofthe invention may contain a photoactive component (e.g. one or morephotoacid generator compounds) one or more resins that are chosen fromamong:

1) a phenolic resin that contains acid-labile groups that can provide achemically amplified positive resist particularly suitable for imagingat 248 nm. Particularly preferred resins of this class include: i)polymers that contain polymerized units of a vinyl phenol and an alkylacrylate, where the polymerized alkyl acrylate units can undergo adeblocking reaction in the presence of photoacid. Exemplary alkylacrylates that can undergo a photoacid-induced deblocking reactioninclude e.g. t-butyl acrylate, t-butyl methacrylate, methyladamantylacrylate, methyl adamantyl methacrylate, and other non-cyclic alkyl andalicyclic acrylates that can undergo a photoacid-induced reaction, suchas polymers in U.S. Pat. Nos. 6,042,997 and 5,492,793; ii) polymers thatcontain polymerized units of a vinyl phenol, an optionally substitutedvinyl phenyl (e.g. styrene) that does not contain a hydroxy or carboxyring substituent, and an alkyl acrylate such as those deblocking groupsdescribed with polymers i) above, such as polymers described in U.S.Pat. No. 6,042,997; and iii) polymers that contain repeat units thatcomprise an acetal or ketal moiety that will react with photoacid, andoptionally aromatic repeat units such as phenyl or phenolic groups; suchpolymers have been described in U.S. Pat. Nos. 5,929,176 and 6,090,526,as well as blends of i) and/or ii) and/or iii);

2) a resin that is substantially or completely free of phenyl or otheraromatic groups that can provide a chemically amplified positive resistparticularly suitable for imaging at sub-200 nm wavelengths such as 193nm. Particularly preferred resins of this class include: i) polymersthat contain polymerized units of a non-aromatic cyclic olefin(endocyclic double bond) such as an optionally substituted norbornene,such as polymers described in U.S. Pat. Nos. 5,843,624, and 6,048,664;ii) polymers that contain alkyl acrylate units such as e.g. t-butylacrylate, t-butyl methacrylate, methyladamantyl acrylate, methyladamantyl methacrylate, and other non-cyclic alkyl and alicyclicacrylates; such polymers have been described in U.S. Pat. No. 6,057,083;European Published Applications EP01008913A1 and EP00930542A1; and U.S.pending patent application Ser. No. 09/143,462, and iii) polymers thatcontain polymerized anhydride units, particularly polymerized maleicanhydride and/or itaconic anhydride units, such as disclosed in EuropeanPublished Application EP01008913A1 and U.S. Pat. No. 6,048,662, as wellas blends of i) and/or ii) and/or iii);

3) a resin that contains repeat units that contain a hetero atom,particularly oxygen and/or sulfur (but other than an anhydride, i.e. theunit does not contain a keto ring atom), and preferable aresubstantially or completely free of any aromatic units. Preferably, theheteroalicyclic unit is fused to the resin backbone, and furtherpreferred is where the resin comprises a fused carbon alicyclic unitsuch as provided by polymerization of a norbornene group and/or ananhydride unit such as provided by polymerization of a maleic anhydrideor itaconic anhydride. Such resins are disclosed in PCT/US01/14914 andU.S. application Ser. No. 09/567,634.

4) a resin that contains fluorine substitution (fluoropolymer), e.g. asmay be provided by polymerization of tetrafluoroethylene, a fluorinatedaromatic group such as fluoro-styrene compound, compounds that comprisea hexafluoroalcohol moiety, and the like. Examples of such resins aredisclosed e.g. in PCT/US99/21912.

The invention further provides methods for forming a photoresist reliefimage and producing an electronic device. The invention also providesnovel articles of manufacture comprising substrates coated with abarrier layer composition of the invention alone or in combination witha photoresist composition.

Other aspects of the invention are disclosed infra.

As discussed above, in a first aspect, methods for processing aphotoresist composition, the methods comprising:

(a) applying on a substrate a photoresist composition;

(b) applying above the photoresist composition a barrier compositionthat comprises one or more components other than resin havingfluorinated backbone substitution;

(c) immersion exposing the photoresist layer to radiation activating forthe photoresist composition.

In such methods, preferably the barrier composition comprises one ormore non-fluorinated resins. Also, the barrier composition comprises oneor more resins that comprise Si atoms, such as one or more organopolysilica resins. In another aspect, the barrier composition maycomprise one or more resins that comprise ester, ether, sulfone, orsulfide groups. The barrier composition also may comprise a componentthat comprises fluorine substitution, which may be the same or differentthan the one or more resins.

In such methods, a fluid having a refractive index of between about 1and about 2 is suitably maintained between an exposure tool and thebarrier composition during the exposing. A variety of photoresists maybe employed in these methods of the invention, e.g. chemically-amplifiedpositive-acting photoresists and negative-acting photoresists.

In some aspects of these methods of the invention the photoresistcomposition will not be not thermally treated prior to applying thebarrier composition. Also, in some aspects of these methods of theinvention, the substrate with the applied photoresist composition andbarrier composition is thermally treated prior to exposing to removesolvent from both the applied photoresist composition and the appliedbarrier composition.

In preferred aspects of the invention, the barrier composition inhibitsmigration of one or more components of the photoresist composition intofluid interposed between the barrier composition and exposure tool usedfor exposing.

Methods and systems of the invention can be used with a variety ofimaging wavelengths, e.g. radiation having a wavelength of less than 300nm such as 248 nm or less than 200 such as 193 nm.

In another embodiment, methods are provided for processing a photoresistcomposition, comprising (a) applying on a substrate a photoresistcomposition; (b) treating the applied photoresist composition with afluid composition; and (c) immersion exposing the photoresist layer toradiation activating for the photoresist composition. The photoresistcomposition may be treated with a variety of fluid compositions,including aqueous fluid compositions as well as fluid compositions thatcomprise one or more organic solvents. In certain aspects, a barriercomposition may be applied above the treated photoresist compositionlayer, preferably a barrier composition as discussed above e.g. abarrier composition that comprises one or more non-fluorinated resins,and/or one or more resins that comprise Si atoms such as one or moreorgano polysilica resins.

In another embodiment, immersion lithography systems are provided suchas a coated substrate system comprising: a substrate having thereon: 1)a coating layer of a photoresist composition; and 2) a coating layer ofa barrier composition above the photoresist composition layer, thebarrier composition comprising one or more non-fluorinated components;and 3) an immersion photolithography exposure tool. The barriercomposition above the treated photoresist composition layer may be asdiscussed above e.g. a barrier composition that comprises one or morenon-fluorinated resins, and/or one or more resins that comprise Si atomssuch as one or more organo polysilica resins.

Particularly preferred organic barrier coating composition of theinvention that are adapted for use with an underlying photoresistcomposition in an immersion photolithography process may comprise ormore silsesquioxane resins and one or more fluorinated organic resins.

Barrier Compositions

As discussed above, preferred barrier layers of the invention includethose that contain one or more non-solvent carrier materials(components) such as one or more resins that do not contain fluorinesubstitution at least along the resin backbone. Suchbackbone-fluorinated resins are typically provided by polymerization ofa fluorinated olefin such as tetrafluoeoethylene and the like. In atleast some aspects, barrier compositions of the invention may containfluorinated resins where the fluorine substitution is of a pendantgroups such as —C(OH)(CF₃)₂ or a pendant alkyl or alicyclic group (e.g.fused or non-fused norbornyl, pendant adamantly, etc.) that has one ormore fluorine atoms.

Barrier compositions of the invention may comprise a variety ofmaterials and preferred barrier composition components are highermolecular weight materials such as materials having a molecular weightin excess of about 500, 1000, 1500 or 2000 daltons. Preferably, thebarrier composition contains only materials that are substantiallylithographically inert, i.e. materials that do not undergo bond-breakingreactions during typical lithographic processing steps of pre-exposureand post-exposure thermal treatments, imaging, or otherwise react withimmersion fluid.

Preferred barrier composition materials include resins that contain Siand/or hetero atom (particularly N, O or S, especially O or S)substitution, or other substitution as discussed above such as zirconiaor hafnia. Preferred barrier composition materials also will besubstantially free of aromatic groups such as phenyl, naphthyl oranthracenyl to avoid excessive absorbance of exposure radiation such assub-300 nm exposure radiation (e.g. 248 nm) or sub-200 nm radiation(e.g. 193 nm). Also preferred are aliphatic polymers that suitablycomprises carbonate, ester, ether, hydroxy or other polar groupsubstitution. Particularly preferred barrier layers for use in animmersion lithography process include resins that comprise Si atoms.

Preferred barrier composition layers will have an index of refraction ofabout 1.4 or greater at 193 nm including about 1.47 or greater at 193nm. Additionally, for any particular system, the index of refraction canbe tuned by changing the composition of the resin(s) of the barriercomposition, including by altering the ratio of components of a resinblend, or composition of any of the resin(s) of a barrier composition.For instance, increasing the amount of organic content in a barrierlayer composition can provided increased refractive index of the layer.

Preferred barrier layer compositions will have a refractive indexbetween of the immersion fluid and the refractive index of thephotoresist at the target exposure wavelength (e.g. 193 nm or 248 nm).

Particularly preferred barrier compositions comprises an organicpolysilica film composition suitably with solubility in polar solventssuch as isopropanol and ethanol. Such organic polysilica films may beprepared using a partial condensate of one or more organosilanes and oneor more silicon-containing cross-linking agents, wherein thecross-linking agent contains >4 hydrolyzable groups. Particularlysuitable silicon-containing cross-linking agents have 5 or 6hydrolyzable groups. As used herein, the term “partial condensate”refers to a silane oligomer or prepolymer or hydrolyzate that is capableof undergoing further condensation reactions to increase its molecularweight.

Such organic polysilica partial condensates may be suitably preparedmethods that include the steps of: a) reacting a mixture including oneor more silanes of formula (I) R_(a)SiY_(4-a) and one or more silanes offormula (H)R¹ _(b)(R²O)_(3-b)Si(R³)_(c)Si(OR⁴)_(3-d)R⁵ _(d) in thepresence of a basic catalyst; and b) reacting the mixture in thepresence of an acidic catalyst; wherein R is hydrogen, (C₁-C₈)alkyl,(C₇-C₁₂)arylalkyl, substituted (C₇-C₁₂)arylalkyl, aryl, and substitutedaryl; Y is any hydrolyzable group; a is an integer of 1 to 2; R¹, R², R⁴and R are independently selected from hydrogen, (C₁-C₆)alkyl,(C₇-C₁₂)arylalkyl, substituted (C₇-C₁₂)aryl-alkyl, aryl, and substitutedaryl; R³ is (C₁-C₁₀)alkyl, —(CH₂)_(h)—, —(CH₂)_(h1)-E_(k)-(CH₂)_(h2)—,—(CH₂)_(h)-Z, arylene, substituted arylene, or arylene ether; E isoxygen, NR⁶ or Z; Z is aryl or substituted aryl; R⁶ is hydrogen,(C₁-C₆)alkyl, aryl or substituted aryl; b and d are each an integer of 0to 2; c is an integer of 0 to 6; and h, h1, h2 and k are independentlyan integer from 1 to 6; provided that at least one of R, R¹, R³ and R⁵is not hydrogen.

In one embodiment, R is (C₁-C₄)alkyl, benzyl, hydroxybenzyl, phenethylor phenyl, and more preferably methyl, ethyl, iso-butyl, tert-butyl orphenyl. Suitable hydrolyzable groups for Y include, but are not limitedto, halo, (C₁-C₆)alkoxy, acyloxy and the like, and preferably chloro and(C₁-C₂)alkoxy. Suitable organosilanes of formula (I) include, but arenot limited to, methyl trimethoxysilane, methyl triethoxysilane, phenyltrimethoxysilane, phenyl triethoxysilane, tolyl trimethoxysilane, tolyltriethoxysilane, propyl tripropoxysilane, iso-propyl triethoxysilane,iso-propyl tripropoxysilane, ethyl trimethoxysilane, ethyltriethoxysilane, iso-butyl triethoxysilane, iso-butyl trimethoxysilane,tert-butyl triethoxysilane, tert-butyl trimethoxysilane, cyclohexyltrimethoxysilane, cyclohexyl triethoxysilane, benzyl trimethoxysilane,benzyl triethoxysilane, phenethyl trimethoxysilane, hydroxybenzyltrimethoxysilane, hydroxyphenylethyl trimethoxysilane andhydroxyphenylethyl triethoxysilane.

Organosilanes of formula (II) preferably include those wherein R¹ and R⁵are independently (C₁-C₄)alkyl, benzyl, hydroxybenzyl, phenethyl orphenyl. Preferably R¹ and R⁵ are methyl, ethyl, tert-butyl, iso-butyland phenyl. In one embodiment, R³ is (C₁-C₁₀)alkyl, —(CH₂)_(h)—,arylene, arylene ether and —(CH₂)_(h1)-E-(CH₂)_(h2). Suitable compoundsof formula (II) include, but are not limited to, those wherein R³ ismethylene, ethylene, propylene, butylene, hexylene, norbornylene,cycloheylene, phenylene, phenylene ether, naphthylene and—CH₂—C₆H₄—CH₂—. In a further embodiment, c is 1 to 4.

Suitable organosilanes of formula (II) include, but are not limited to,bis(trimethoxysilyl)methane, bis(triethoxysilyl)methane,bis(triphenoxysilyl)methane, bis(dimethoxymethylsilyl)methane,bis(diethoxymethyl-silyl)methane, bis(dimethoxyphenylsilyl)methane,bis(diethoxyphenylsilyl)methane, bis(methoxydimethylsilyl)methane,bis(ethoxydimethylsilyl)methane, bis(methoxy-diphenylsilyl)methane,bis(ethoxydiphenylsilyl)methane, bis(trimethoxysilyl)ethane,bis(triethoxysilyl)ethane, bis(triphenoxysilyl)ethane,bis(dimethoxymethylsilyl) ethane, bis(diethoxymethylsilyl)ethane,bis(dimethoxyphenylsilyl)ethane, bis(diethoxyphenylsilyl)ethane,bis(methoxydimethylsilyl)ethane, bis(ethoxydimethylsilyl)ethane,bis(methoxy-diphenylsilyl)ethane, bis(ethoxydiphenylsilyl)ethane,1,3-bis(trimethoxysilyl))propane, 1,3-bis(triethoxysilyl)propane,1,3-bis(triphenoxysilyl)propane, 1,3-bis(dimethoxy-methylsilyl)propane,1,3-bis(diethoxymethylsilyl)propane,1,3-bis(dimethoxyphenyl-silyl)propane,1,3-bis(diethoxyphenylsilyl)propane,1,3-bis(methoxydimehylsilyl)propane,1,3-bis(ethoxydimethylsilyl)propane,1,3-bis(methoxydiphenylsilyl)propane, and1,3-bis(ethoxydiphenylsilyl)propane.

Suitable organic polysilica materials include, but are not limited to,silsesquioxanes, partially condensed halosilanes or alkoxysilanes suchas partially condensed by controlled hydrolysis tetraethoxysilane havingnumber average molecular weight of 500 to 20,000, organically modifiedsilicates having the composition RSiO₃, O₃SiRSiO₃, R₂SiO₂ and O₂SiR₃SiO₂wherein R is an organic substituent, and partially condensedorthosilicates having Si(OR)₄ as the monomer unit. Silsesquioxanes arepolymeric silicate materials of the type RSiO_(1.5) where R is anorganic substituent. Suitable silsesquioxanes are alkyl silsesquioxanes;aryl silsesquioxanes; alkyl/aryl silsesquioxane mixtures; and mixturesof alkyl silsesquioxanes. Silsesquioxane materials include homopolymersof silsesquioxanes, copolymers of silsesquioxanes or mixtures thereof.Such materials are generally commercially available or may be preparedby known methods.

In an alternate embodiment, the organic polysilica materials may containa wide variety of other monomers in addition to the silicon-containingmonomers described above. For example, the organic polysilica materialsmay further comprise a second cross-linking agent, and carbosilanemoieties.

Suitable second cross-linking agents may be any known cross-linkers forsilicon-containing materials. Typical second cross-linking agentsinclude silanes of formula (III) M_(n)(OR¹¹)_(n) wherein M is aluminum,titanium, zirconium, hafnium, silicon, magnesium, or boron; R¹¹ is(C₁-C₆)alkyl, acyl, or Si(OR¹²)₃; R¹² is (C₁-C₆)alkyl or acyl; and n isthe valence of M. In one embodiment, R¹¹ is methyl, ethyl, propyl orbutyl. In another embodiment, M is aluminum, titanium, zirconium,hafnium or silicon. It will be appreciated by those skilled in the artthat a combination of such second cross-linkers may be used. The ratioof the mixture of silanes of formulae (I) and (II) to such secondcross-linking agents organosilanes is typically from 99:1 to 1:99,preferably from 95:5 to 5:95, more preferably from 90:10 to 10:90.

Carbosilane moieties refer to moieties having a (Si—C)_(x) structure,such as (Si-A)_(x) structures wherein A is a substituted orunsubstituted alkylene or arylene, such as SiR₃CH₂—, —SiR₂CH₂—,═SiRCH₂—, and ≡SiCH₂—, where R is usually hydrogen but may be anyorganic or inorganic radical. Suitable inorganic radicals includeorganosilicon, siloxyl, or silanyl moieties. These carbosilane moietiesare typically connected “head-to-tail”, i.e. having Si—C—Si bonds, insuch a manner that a complex, branched structure results. Particularlyuseful carbosilane moieties are those having the repeat units(SiH_(x)CH₂) and (SiH_(y-1)(CH═CH₂)CH₂), where x=0 to 3 and y=1 to 3.These repeat units may be present in the organic polysilica resins inany number from 1 to 100,000, and preferably from 1 to 10,000. Suitablecarbosilane precursors are those disclosed in U.S. Pat. No. 5,153,295(Whitmarsh et al.) and U.S. Pat. No. 6,395,649 (Wu).

The organic polysilica partial condensates may be prepared by reactingone or more tri-or di-functional organo silanes such as those of formulaI, one or more silicon-containing cross-linking agents such as those offormula II, and typically water, for a period of time sufficient tohydrolyze (or partially condense) the silanes to form a partialcondensate having the desired weight average molecular weight.Typically, the reaction temperature is 78-80° C. due to the boilingpoint of ethanol. The amount of water is typically from 0.1 to 2.0 moleequivalents, more typically from 0.25 to 1.75 mole equivalents, and evenmore typically from 0.75 to 1.5 mole equivalents. An acidic or basiccatalyst is typically used. Suitable acids and bases include strongacids and strong bases such as hydrochloric acid and tetramethylammoniumhydroxide respectively weak acids and bases such as acetic acid ortriethyl amine respectively. Typically strong acid catalyst likehydrochloric acid is used to catalyze the hydrolysis and condensationreaction of the silanes. The silanes and water are typically reactedfrom 0.5 to 48 hours, although longer or shorter times may be used.Particularly suitable reaction times are from 1 to 24 hours. The moleratios of the silanes may vary over a wide range. The mole ratio of theone or more silanes of formula (I) to the one or more silanes of formula(II) is from 99:1 to 1:99, particularly from 95:5 to 5:95, moreparticularly from 90:10 to 10:90, and still more particularly from 80:20to 20:80.

Suitable organic polysilica partial condensates for use in barrier layercompositions may have a wide range of molecular weights. Typically, thepartial condensates have a weight average molecular weight of ≦20,000,although higher molecular weights may be used. More typically, theweight average molecular weight is ≦15,000, still more typically≦10,000, and most typically ≦5,000.

Following formation of the organic polysilica partial condensates, andafter optionally removing the acidic catalyst, a stabilizing agent maybe optionally added to the partial condensates. Such stabilizing agentsare preferably organic acids. Any organic acid having at least 2 carbonsand having an acid dissociation constant (“pKa”) of about 1 to about 4at 25° C. is suitable. Preferred organic acids have a pKa of about 1.1to about 3.9, and more preferably about 1.2 to about 3.5. Organic acidscapable of functioning as chelating agents are preferred. Such chelatingorganic acids include polycarboxylic acids such as di-, tri-, tetra- andhigher carboxylic acids, and carboxylic acids substituted with one ormore of hydroxyls, ethers, ketones, aldehydes, amine, amides, imines,thiols and the like. Preferred chelating organic acids arepolycarboxylic acids and hydroxy-substituted carboxylic acids. The term“hydroxy-substituted carboxylic acids” includes hydroxy-substitutedpolycarboxylic acids. Suitable organic acids include, but are notlimited to: oxalic acid, malonic acid, methylmalonic acid,dimethylmalonic acid, maleic acid, malic acid, citramalic acid, tartaricacid, phthalic acid, citric acid, glutaric acid, glycolic acid, lacticacid, pyruvic acid, oxalacetic acid, ketoglutaric acid, salicylic acidand acetoacetic acid. Preferred organic acids are oxalic acid, malonicacid, dimethylmalonic acid, citric acid and lactic acid, and morepreferably malonic acid. Mixtures of organic acids may be advantageouslyused in the present invention. Those skilled in the art will realizethat polycarboxylic acids have a pKa value for each carboxylic acidmoiety in the compound. Only one of the pKa values in suchpolycarboxylic acids needs to be within the range of 1 to 4 at 25° C.for the organic acid to be suitable for use in the present invention.Such stabilizing agents are typically used in an amount of 1 to 10,000ppm and preferably from 10 to 1000 ppm. Such stabilizing agents functionto retard further condensation of the material and extend the shelf-lifeof the partial condensates.

As discussed above, a variety of other materials also will be useful ascomponents of barrier layer compositions of the invention. Moreparticularly, suitable organic polymers that do not containperfluoro-backbone substitution may be selected from any non lightadsorbing deep UV polymers of, such as, but not limited to,poly(alkylene oxide) monomers, poly(meth)acrylic acid, poly(meth)acrylamides, polyh, aromatic (meth)acrylates, vinyl aromaticmonomers, nitrogen-containing compounds and their thio-analogs,substituted ethylene monomers, and combinations thereof.

Particularly useful non-fluorinated organic polymers are thosecontaining as polymerized units at least one compound selected fromsilyl containing monomers or poly(alkylene oxide) monomers and one ormore cross-linking agents. Such porogens are described in U.S. Pat. No.6,271,273. Suitable silyl containing monomers include, but are notlimited to, vinyltrimethylsilane, vinyltriethylsilane,vinyltrimethoxysilane, vinyltriethoxysilane, trimethoxysilylpropyl(meth)acrylate, divinylsilane, trivinylsilane, dimethyldivinylsilane,divinylmethylsilane, methyltrivinylsilane, diphenyldivinylsilane,divinylphenylsilane, trivinylphenylsilane, divinylmethylphenylsilane,tetravinylsilane, dimethylvinyldisiloxane, poly(methylvinylsiloxane),poly(vinylhydrosiloxane), poly(phenylvinylsiloxane),allyloxy-tert-butyfldimethylsilane, allyloxytrimethylsilane,allyltriethoxysilane, allyltri-iso-propylsilane, allyltrimethoxysilane,allyltrimethylsilane, allyltriphenylsilane, diethoxy methylvinylsilane,diethyl methylvinylsilane, dimethyl ethoxyvinylsilane, dimethylphenylvinylsilane, ethoxy diphenylvinylsilane, methylbis(trimethylsilyloxy)vinylsilane, triacetoxyvinylsilane,triethoxyvinylsilane, triethylvinylsilane, triphenylvinylsilane,tris(trimethylsilyloxy)vinylsilane, vinyloxytrimethylsilane and mixturesthereof. The amount of silyl containing monomer useful to form theporogens of the present invention is typically from 1 to 99% wt, basedon the total weight of the monomers used. It is preferred that the silylcontaining monomers are present in an amount of from 1 to 80% wt, andmore preferably from 5 to 75% wt.

Suitable poly(alkylene oxide) monomers include, but are not limited to,poly(propylene oxide) monomers, poly(ethylene oxide) monomers,poly(ethylene oxide/propylene oxide) monomers, poly(propylene glycol)(meth)acrylates, poly(propylene glycol) alkyl ether (meth)acrylates,poly(propylene glycol) phenyl ether (meth)acrylates, poly(propyleneglycol) 4-nonylphenol ether (meth)acrylates, poly(ethylene glycol)(meth)acrylates, poly(ethylene glycol) alkyl ether (meth)acrylates,poly(ethylene glycol) phenyl ether (meth)acrylates,poly(propylene/ethylene glycol) alkyl ether (meth)acrylates and mixturesthereof. Preferred poly(alkylene oxide) monomers includetrimethoylolpropane ethoxylate tri(meth)acrylate, trimethoylolpropanepropoxylate tri(meth)acrylate, poly(propylene glycol) methyl etheracrylate, and the like. Particularly suitable poly(propylene glycol)methyl ether acrylate monomers are those having a molecular weight inthe range of from 200 to 2000. The poly(ethylene oxide/propylene oxide)monomers useful in the present invention may be linear, block or graftcopolymers. Such monomers typically have a degree of polymerization offrom 1 to 50, and preferably from 2 to 50. Typically, the amount ofpoly(alkylene oxide) monomers useful in the porogens of the presentinvention is from 1 to 99% wt, based on the total weight of the monomersused. The amount of poly(alkylene oxide) monomers is preferably from 2to 90% wt, and more preferably from 5 to 80% wt.

The silyl containing monomers and the poly(alkylene oxide) monomers maybe used either alone or in combination to form the porogens of thepresent invention. In general, the amount of the silyl containingmonomers or the poly(alkylene oxide) monomers needed to compatiblize theporogen with the dielectric matrix depends upon the level of porogenloading desired in the matrix, the particular composition of the organopolysilica dielectric matrix, and the composition of the porogenpolymer. When a combination of silyl containing monomers and thepoly(alkylene oxide) monomers is used, the amount of one monomer may bedecreased as the amount of the other monomer is increased. Thus, as theamount of the silyl containing monomer is increased in the combination,the amount of the poly(alkylene oxide) monomer in the combination may bedecreased.

Exemplary cross-linkers include, but are not limited to:trivinylbenzene, divinyltoluene, divinylpyridine, divinylnaphthalene anddivinylxylene; and such as ethyleneglycol diacrylate, trimethylolpropanetriacrylate, diethyleneglycol divinyl ether, trivinylcyclohexane, allylmethacrylate, ethyleneglycol dimethacrylate, diethyleneglycoldimethacrylate, propyleneglycol dimethacrylate, propyleneglycoldiacrylate, trimethylolpropane trimethacrylate, divinyl benzene,glycidyl methacrylate, 2,2-dimethylpropane 1,3 diacrylate, 1,3-butyleneglycol diacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butanedioldiacrylate, diethylene glycol diacrylate, diethylene glycoldimethacrylate, 1,6-hexanediol diacrylate, 1,6-hexanedioldimethacrylate, tripropylene glycol diacrylate, triethylene glycoldimethacrylate, tetraethylene glycol diacrylate, polyethylene glycol 200diacrylate, tetraethylene glycol dimethacrylate, polyethylene glycoldimethacrylate, ethoxylated bisphenol A diacrylate, ethoxylatedbisphenol A dimethacrylate, polyethylene glycol 600 dimethacrylate,poly(butanediol) diacrylate, pentaerythritol triacrylate,trimethylolpropane triethoxy triacrylate, glyceryl propoxy triacrylate,pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate,dipentaerythritol monohydroxypentaacrylate, and mixtures thereof. Silylcontaining monomers that are capable of undergoing cross-linking mayalso be used as cross-linkers, such as, but not limited to,divinylsilane, trivinylsilane, dimethyldivinylsilane,divinylmethylsilane, methyltrivinylsilane, diphenyldivinylsilane,divinylphenylsilane, trivinylphenylsilane, divinylmethylphenylsilane,tetravinylsilane, dimethylvinyldisiloxane, poly(methylvinylsiloxane),poly(vinylhydrosiloxane), poly(phenylvinylsiloxane), tetraallylsilane,1,3-dimethyl tetravinyldisiloxane, 1,3-divinyl tetramethyldisiloxane andmixtures thereof.

Preferred solvent materials to formulate and cast a barrier compositionare any which dissolve or disperse the component(s) of the barrier layercomposition (e.g., one or more resins) but do not appreciably dissolvean underlying photoresist layer. More particularly, suitable solvents toformulate a barrier composition include one or more of, but are notlimited to, alcohols such as isopropanol, n-butanol, alkylene glycols,such as propylene glycol. Alternatively non-polar solvents such asaliphatic and aromatic hydrocarbons such as dodecane, isooctane,mesitylene and xylenes may be used.

A barrier composition may be suitably preferred by admixture of one ormore solid components (e.g. one or more resins) into one or more polarsolvents such as those identified above or alternatively one or morenon-polar solvents such as the aliphatic and aromatic hydrocarbonsidentified above. See the examples which follow for exemplary proceduresfor preparation of barrier compositions of the invention.

As used herein, the following abbreviations shall have the followingmeanings, unless the context clearly indicates otherwise: ° C.=degreescentigrade; μm=micron=micrometer; UV=ultraviolet; rpm=revolutions perminute; min.=minute; hr.=hour; nm=nanometer; g=gram; % wt=% by weight;L=liter; mL=milliliter; ppm=parts per million; GPa=gigaPascals;Mw=weight average molecular weight; Mn=number average molecular weight.

The term “(meth)acrylic” includes both acrylic and methacrylic and theterm “(meth)acrylate” includes both acrylate and methacrylate. Likewise,the term “(meth)acrylamide” refers to both acrylamide andmethacrylamide. “Alkyl” includes straight chain, branched and cyclicalkyl groups. The term “polymer” includes both homopolymers andcopolymers. The terms “oligomer” and “oligomeric” refer to dimers,trimers, tetramers and the like. “Monomer” refers to any ethylenicallyor acetylenically unsaturated compound capable of being polymerized.Such monomers may contain one or more double or triple bonds.“Cross-linker” and “cross-linking agent” are used interchangeablythroughout this specification and refer to a compound having two or moregroups capable of being polymerized. As used herein, the terms “cure”and “curing” refer to polymerization, condensation or any other reactionwhere the molecular weight of a compound is increased. The step ofsolvent removal alone is not considered “curing” as used in thisspecification. However, a step involving both solvent removal and, e.g.,polymerization is within the term “curing” as used herein. The term“organic polysilica” material (or organo siloxane) refers to a materialincluding silicon, carbon, oxygen and hydrogen atoms. “Silane” as usedherein refers to a silicon-containing material capable of undergoinghydrolysis and/or condensation. The articles “a” and “an” refer to thesingular and the plural.

Photoresists

A wide variety of photoresist compositions may be used in combinationwith barrier layer compositions and processes of the invention.

As discussed above, preferred photoresists for use in accordance withthe invention include positive-acting or negative-acting chemicallyamplified photoresists, i.e. negative-acting resist compositions whichundergo a photoacid-promoted crosslinking reaction to render exposedregions of a coating layer of the resist less developer soluble thanunexposed regions, and positive-acting resist compositions which undergoa photoacid-promoted deprotection reaction of acid labile groups of oneor more composition components to render exposed regions of a coatinglayer of the resist more soluble in an aqueous developer than unexposedregions. Ester groups that contain a tertiary non-cyclic alkyl carbon(e.g. t-butyl) or a tertiary alicyclic carbon (e.g. methyladamantyl)covalently linked to the carboxyloxygen of the ester are often preferredphotoacid-labile groups of resins employed in photoresists of theinvention. Acetal photoacid-labile groups also will be preferred.

The photoresists of the invention typically comprise a resin componentand a photoactive component of the invention as described above.Preferably the resin has functional groups that impart alkaline aqueousdevelopability to the resist composition. For example, preferred areresin binders that comprise polar functional groups such as hydroxyl orcarboxylate. Preferably a resin component is used in a resistcomposition in an amount sufficient to render the resist developablewith an aqueous alkaline solution.

For imaging at wavelengths greater than 200 nm, such as 248 nm, phenolicresins are typically preferred. Preferred phenolic resins are poly(vinylphenols) which may be formed by block polymerization, emulsionpolymerization or solution polymerization of the corresponding monomersin the presence of a catalyst. Vinylphenols useful for the production ofpolyvinyl phenol resins may be prepared, for example, by hydrolysis ofcommercially available coumarin or substituted coumarin, followed bydecarboxylation of the resulting hydroxy cinnamic acids. Usefulvinylphenols may also be prepared by dehydration of the correspondinghydroxy alkyl phenols or by decarboxylation of hydroxy cinnamic acidsresulting from the reaction of substituted or nonsubstitutedhydroxybenzaldehydes with malonic acid. Preferred polyvinylphenol resinsprepared from such vinylphenols have a molecular weight range of fromabout 2,000 to about 60,000 daltons.

Also preferred for imaging at wavelengths greater than 200 nm, such as248 nm are chemically amplified photoresists that comprise in admixturea photoactive component and a resin component that comprises a copolymercontaining both phenolic and non-phenolic units. For example, onepreferred group of such copolymers has acid labile groups substantially,essentially or completely only on non-phenolic units of the copolymer,particularly alkylacrylate photoacid-labile groups, i.e. aphenolic-alkyl acrylate copolymer. One especially preferred copolymerbinder has repeating units x and y of the following formula:

wherein the hydroxyl group be present at either the ortho, meta or parapositions throughout the copolymer, and R′ is substituted orunsubstituted alkyl having 1 to about 18 carbon atoms, more typically 1to about 6 to 8 carbon atoms. Tert-butyl is a generally preferred R′group. An R′ group may be optionally substituted by e.g. one or morehalogen (particularly F, Cl or Br), C₁₋₈ alkoxy, C₂₋₈ alkenyl, etc. Theunits x and y may be regularly alternating in the copolymer, or may berandomly interspersed through the polymer. Such copolymers can bereadily formed. For example, for resins of the above formula, vinylphenols and a substituted or unsubstituted alkyl acrylate such ast-butylacrylate and the like may be condensed under free radicalconditions as known in the art. The substituted ester moiety, i.e.R′—O—C(═O)—, moiety of the acrylate units serves as the acid labilegroups of the resin and will undergo photoacid induced cleavage uponexposure of a coating layer of a photoresist containing the resin.Preferably the copolymer will have a M_(w) of from about 8,000 to about50,000, more preferably about 15,000 to about 30,000 with a molecularweight distribution of about 3 or less, more preferably a molecularweight distribution of about 2 or less. Non-phenolic resins, e.g. acopolymer of an alkyl acrylate such as t-butylacrylate ort-butylmethacrylate and a vinyl alicyclic such as a vinyl norbornanyl orvinyl cyclohexanol compound, also may be used as a resin binder incompositions of the invention. Such copolymers also may be prepared bysuch free radical polymerization or other known procedures and suitablywill have a Mw of from about 8,000 to about 50,000, and a molecularweight distribution of about 3 or less.

Other preferred resins that have acid-labile deblocking groups for usein a positive-acting chemically-amplified photoresist of the inventionhave been disclosed in European Patent Application 0829766A2 of theShipley Company (resins with acetal and ketal resins) and EuropeanPatent Application EP0783136A2 of the Shipley Company (terpolymers andother copolymers including units of 1) styrene; 2) hydroxystyrene; and3) acid labile groups, particularly alkyl acrylate acid labile groupssuch as t-butylacrylate or t-butylmethacrylate). In general, resinshaving a variety of acid labile groups will be suitable, such as acidsensitive esters, carbonates, ethers, imides, etc. The photoacid labilegroups will more typically be pendant from a polymer backbone, althoughresins that have acid labile groups that are integral to the polymerbackbone also may be employed.

As discussed above, for imaging at sub-200 nm wavelengths such as 193nm, preferably a photoresist is employed that contains one or morepolymers that are substantially, essentially or completely free ofphenyl or other aromatic groups. For example, for sub-200 nm imaging,preferred photoresist polymers contain less than about 5 mole percentaromatic groups, more preferably less than about 1 or 2 mole percentaromatic groups, more preferably less than about 0.1, 0.02, 0.04 and0.08 mole percent aromatic groups and still more preferably less thanabout 0.01 mole percent aromatic groups. Particularly preferred polymersare completely free of aromatic groups. Aromatic groups can be highlyabsorbing of sub-200 nm radiation and thus are undesirable for polymersused in photoresists imaged with such short wavelength radiation.

Suitable polymers that are substantially or completely free of aromaticgroups and may be formulated with a PAG of the invention to provide aphotoresist for sub-200 nm imaging are disclosed in European applicationEP930542A1 and U.S. Pat. Nos. 6,692,888 and 6,680,159, all of theShipley Company.

Suitable polymers that are substantially or completely free of aromaticgroups suitably contain acrylate units such as photoacid-labile acrylateunits as may be provided by polymerization of methyladamanatylacrylate,methyladamantylmethacrylate, ethylfenchylacrylate,ethylfenchylmethacrylate, and the like; fused non-aromatic alicyclicgroups such as may be provided by polymerization of a norbornenecompound or other alicyclic compound having an endocyclic carbon-carbondouble bond; an anhydride such as may be provided by polymerization ofmaleic anhydride and/or itaconic anhydride; and the like.

Preferred negative-acting compositions of the invention comprise amixture of materials that will cure, crosslink or harden upon exposureto acid, and a photoactive component of the invention. Particularlypreferred negative acting compositions comprise a resin binder such as aphenolic resin, a crosslinker component and a photoactive component ofthe invention. Such compositions and the use thereof has been disclosedin European Patent Applications 0164248 and 0232972 and in U.S. Pat. No.5,128,232 to Thackeray et al. Preferred phenolic resins for use as theresin binder component include novolaks and poly(vinylphenol)s such asthose discussed above. Preferred crosslinkers include amine-basedmaterials, including melamine, glycolurils, benzoguanamine-basedmaterials and urea-based materials. Melamine-formaldehyde resins aregenerally most preferred. Such crosslinkers are commercially available,e.g. the melamine resins sold by American Cyanamid under the trade namesCymel 300, 301 and 303. Glycoluril resins are sold by American Cyanamidunder trade names Cymel 1170, 1171, 1172, urea-based resins are soldunder the trade names of Beetle 60, 65 and 80, and benzoguanamine resinsare sold under the trade names Cymel 1123 and 1125.

For imaging at sub-200 nm wavelengths such as 193 nm, preferrednegative-acting photoresists are disclosed in WO 03077029 to the ShipleyCompany.

Photoresists of the invention also may contain other materials. Forexample, other optional additives include actinic and contrast dyes,anti-striation agents, plasticizers, speed enhancers, sensitizers (e.g.for use of a PAG of the invention at longer wavelengths such as I-line(i.e. 365 nm) or G-line wavelengths), etc. Such optional additivestypically will be present in minor concentration in a photoresistcomposition except for fillers and dyes which may be present inrelatively large concentrations such as, e.g., in amounts of from 5 to30 percent by weight of the total weight of a resist's dry components.

A preferred optional additive of resists of the invention is an addedbase, e.g. a caprolactam, which can enhance resolution of a developedresist relief image. The added base is suitably used in relatively smallamounts, e.g. about 1 to 10 percent by weight relative to the PAG, moretypically 1 to about 5 weight percent. Other suitable basic additivesinclude ammonium sulfonate salts such as piperidinium p-toluenesulfonateand dicyclohexylammonium p-toluenesulfonate; alkyl amines such astripropylamine and dodecylamine; aryl amines such as diphenylamine,triphenylamine, aminophenol,2-(4-aminophenyl)-2-(4-hydroxyphenyl)propane, etc.

The resin component of resists useful in accordance with the inventionare typically used in an amount sufficient to render an exposed coatinglayer of the resist developable such as with an aqueous alkalinesolution. More particularly, a resin binder will suitably comprise 50 toabout 90 weight percent of total solids of the resist. The photoactivecomponent should be present in an amount sufficient to enable generationof a latent image in a coating layer of the resist. More specifically,the photoactive component will suitably be present in an amount of fromabout 1 to 40 weight percent of total solids of a resist. Typically,lesser amounts of the photoactive component will be suitable forchemically amplified resists.

The resist compositions of the invention also comprise a photoacidgenerator (i.e. “PAG”) that is suitably employed in an amount sufficientto generate a latent image in a coating layer of the resist uponexposure to activating radiation. Preferred PAGs for imaging at 193 nmand 248 nm imaging include imidosulfonates such as compounds of thefollowing formula:

wherein R is camphor, adamantane, alkyl (e.g. C₁₋₁₂ alkyl) andperfluoroalkyl such as perfluoro(C₁₋₁₂alkyl), particularlyperfluorooctanesulfonate, perfluorononanesulfonate and the like. Aspecifically preferred PAG isN-[(perfluorooctanesulfonyl)oxy]-5-norbornene-2,3-dicarboximide.

Sulfonate compounds are also suitable PAGs, particularly sulfonatesalts. Two suitable agents for 193 nm and 248 nm imaging are thefollowing PAGS 1 and 2:

Such sulfonate compounds can be prepared as disclosed in European PatentApplication 96118111.2 (publication number 0783136), which details thesynthesis of above PAG 1.

Also suitable are the above two iodonium compounds complexed with anionsother than the above-depicted camphorsulfonate groups. In particular,preferred anions include those of the formula RSO₃— where R isadamantane, alkyl (e.g. C₁₋₁₂ alkyl) and perfluoroalkyl such asperfluoro (C₁₋₁₂alkyl), particularly perfluorooctanesulfonate,perfluorobutanesulfonate and the like.

Other known PAGS also may be employed in photoresists used in accordancewith the invention. Particularly for 193 nm imaging, generally preferredare PAGS that do not contain aromatic groups, such as theabove-mentioned imidosulfonates, in order to provide enhancedtransparency.

A preferred optional additive of resists of the invention is an addedbase, particularly tetrabutylammonium hydroxide (TBAH), ortetrabutylammonium lactate, which can enhance resolution of a developedresist relief image. For resists imaged at 193 nm, a preferred addedbase is a hindered amine such as diazabicyclo undecene ordiazabicyclononene. The added base is suitably used in relatively smallamounts, e.g. about 0.03 to 5 percent by weight relative to the totalsolids.

Photoresists used in accordance with the invention also may containother optional materials. For example, other optional additives includeanti-striation agents, plasticizers, speed enhancers, etc. Such optionaladditives typically will be present in minor concentrations in aphotoresist composition except for fillers and dyes which may be presentin relatively large concentrations, e.g., in amounts of from about 5 to30 percent by weight of the total weight of a resist's dry components.

Negative-acting photoresists of the invention typically will contain acrosslinking component, preferably as a separate resist component.Amine-based crosslinkers often will be preferred such as a melamine,e.g. the Cymel melamine resins.

The photoresists used in accordance with the invention are generallyprepared following known procedures. For example, a resist of theinvention can be prepared as a coating composition by dissolving thecomponents of the photoresist in a suitable solvent such as, e.g., aglycol ether such as 2-methoxyethyl ether (diglyme), ethylene glycolmonomethyl ether, propylene glycol monomethyl ether; propylene glycolmonomethyl ether acetate; lactates such as ethyl lactate or methyllactate, with ethyl lactate being preferred; propionates, particularlymethyl propionate, ethyl propionate and ethyl ethoxy propionate; aCellosolve ester such as methyl Cellosolve acetate; an aromatichydrocarbon such toluene or xylene; or a ketone such as methylethylketone, cyclohexanone and 2-heptanone. Typically the solids content ofthe photoresist varies between 5 and 35 percent by weight of the totalweight of the photoresist composition. Blends of such solvents also aresuitable.

Lithographic Processing

Liquid photoresist compositions may be applied to a substrate such as byspinning, dipping, roller coating or other conventional coatingtechnique. When spin coating, the solids content of the coating solutioncan be adjusted to provide a desired film thickness based upon thespecific spinning equipment utilized, the viscosity of the solution, thespeed of the spinner and the amount of time allowed for spinning.

Photoresist compositions used in accordance with the invention aresuitably applied to substrates conventionally used in processesinvolving coating with photoresists. For example, the composition may beapplied over silicon wafers or silicon wafers coated with silicondioxide for the production of microprocessors and other integratedcircuit components. Aluminum-aluminum oxide, gallium arsenide, ceramic,quartz, copper, glass substrates and the like are also suitablyemployed. Photoresists also may be suitably applied over anantireflective layer, particularly an organic antireflective layer.

As discussed above, an applied photoresist composition layer may bepreferably treated with a solvent composition, e.g. a solventcomposition comprising one or more aqueous and/or organic solvents suchas an alcohol. Such solvent composition-treatment can reduce undesiredmigration of photoresist materials into immersion fluid during immersionexposure.

If a barrier composition layer is employed, the barrier composition canbe applied over the photoresist composition by any suitable methods,with spin coating being preferred.

Following coating of the photoresist onto a surface, it may be dried byheating to remove the solvent until preferably the photoresist coatingis tack free, or as discussed above, the photoresist layer may be driedafter the barrier layer composition has been applied and the solventfrom both the photoresist composition and barrier composition layerssubstantially removed in a single thermal treatment step.

The photoresist layer (with overcoated barrier composition layer, ifpresent) in then exposed in an immersion lithography system, i.e. wherethe space between the exposure tool (particularly the projection lens)and the photoresist coated substrate is occupied by an immersion fluid,such as water or water mixed with one or more additives such as cesiumsulfate which can provide a fluid of enhanced refractive index.Preferably the immersion fluid (e.g., water) has been treated to avoidbubbles, e.g. water can be degassed to avoid nanobubbles.

References herein to “immersion exposing” or other similar termindicates that exposure is conducted with such a fluid layer (e.g. wateror water with additives) interposed between an exposure tool and thecoated photoresist composition layer.

The photoresist composition layer is then suitably patterned exposed toactivating radiation with the exposure energy typically ranging fromabout 1 to 100 mJ/cm², dependent upon the exposure tool and thecomponents of the photoresist composition. References herein to exposinga photoresist composition to radiation that is activating for thephotoresist indicates that the radiation is capable of forming a latentimage in the photoresist such as by causing a reaction of thephotoactive component (e.g. producing photoacid from the photoacidgenerator compound).

As discussed above, photoresist compositions are preferablyphotoactivated by a short exposure wavelength, particularly a sub-300and sub-200 nm exposure wavelength, with 248 nm and 193 nm beingparticularly preferred exposure wavelengths as well as EUV and 157 nm.

Following exposure, the film layer of the composition is preferablybaked at temperatures ranging from about 70° C. to about 160° C.Thereafter, the film is developed, preferably by treatment with anaqueous based developer such as quaternary ammonium hydroxide solutionssuch as a tetra-alkyl ammonium hydroxide solution; various aminesolutions preferably a 0.26 N tetramethylammonium hydroxide, such asethyl amine, n-propyl amine, diethyl amine, di-n-propyl amine, triethylamine, or methyldiethyl amine; alcohol amines such as diethanol amine ortriethanol amine; cyclic amines such as pyrrole, pyridine, etc. Ingeneral, development is in accordance with procedures recognized in theart.

Following development of the photoresist coating over the substrate, thedeveloped substrate may be selectively processed on those areas bared ofresist, for example by chemically etching or plating substrate areasbared of resist in accordance with procedures known in the art. For themanufacture of microelectronic substrates, e.g., the manufacture ofsilicon dioxide wafers, suitable etchants include a gas etchant, e.g. ahalogen plasma etchant such as a chlorine or fluorine-based etchant sucha Cl₂ or CF₄/CHF₃ etchant applied as a plasma stream. After suchprocessing, resist may be removed from the processed substrate usingknown stripping procedures.

The following non-limiting examples are illustrative of the invention.

EXAMPLE 1 Barrier Composition Preparation

A top layer (barrier) coating solution was prepared by charging apolyethylene container with 10.62 g of a hydrozylate of 55 wt %methyltriethoxysilane and 45 wt % tetraethylorthosilicate at a solutionsolids of 27% in propylene glycol monomethylether acetate and 1.99 g ofan acrylate copolymer comprised of 90 wt % Cognis Photomer 8061 and 10wt % UCB TMPTA-N at a solution solids of 93% in propylene glycolmonomethyl ether acetate solvent. The organo-polysilica was prepared asdescribed above and in published patent documents of the Shipley Companywhile the organic polymer was prepared according to the method disclosedin U.S. Pat. No. 6,271,273 (You et al.) and U.S. Pat. No. 6,420,441.

To the polymers was added 215 g of isopropanol and the solution wasshaken to form a homogeneous solution. The sample was ion-exchanged thrua bed of Amberlite IRN 150, a product of the Rohm and Haas Company,Philadelphia Pa., and then filtered through a 0.2 micronpolytetarafluoroethylene filter disk.

EXAMPLE 2-6 Barrier Compositions Preparation

Based on the procedure outlined in Example 1, additional top coatsamples were prepared from the same organopolysilica polymer describedin Example 1. The composition of organic polymer is shown in Table 1 andthe solution solids of each sample was 15% by weight (balance ofcomposition isopropanol (IPA) carrier solvent). TABLE 1 Composition ofTop Layer Coating in Examples 2-6 Organo- Organic Isopro- Exam-polysilica Polymer Organic Polymer Ratio panol ple Grams GramsComposition Wt % Grams 2 1.848 2.136 HOPPOMA/EDMA/ 85/10/5 25.006 DMAEMA3 1.848 2.136 PPG260A/AA/ 87/3/10 25.006 TMPTMA 4 1.848 2.136HOPPOMA/EDMA/ 85/10/5 25.006 MAA 5 1.848 2.136 2-EHA/ 60/30/10 25.006α-MeStyrene/ TMPTA 6 3.911 0.0 None — 25.089

EXAMPLE 7 Processing of Barrier Compositions

Coating samples of Examples 1-6 were spin coated on a Site ServicesTractrix 200 mm track. The solutions were disposed from a pipette onto awafer while the wafer was stationary. The 200 mm wafer was spun at aspin speed of 1500-2500 rpm to achieve the desired film thickness. Inthe process of spinning the film, excess solvent is also removed fromthe film. To remove the remainder of the solvent from the film the waferwas heated on a hot plate at 90° C. to dry the film.

Coating Process

The top layer coating compositions were spin coated onto uncoatedsilicon wafers to determine thickness and optical properties of thecoatings. The samples were then spin coated on to silicon wafers where amethacrylate based 193 nm photoresist had already been deposited. Theresist was deposit from propyleneglycol monomethyl ether acetate andthen optionally cured at 120° C. for 1 minute. The results of anisopropanol (IPA) rinse step or top layer coating deposition on top ofthe resist layer are shown in tables 2 and 3. For the soft bake resistsample, the coating was unaffected by the IPA rinse step with minimalfilm loss. For the non-soft baked sample the film thickness loss wasapproximately 25 nm. In both cases, good quality top layer films wereprepared from deposition of Example 1. TABLE 2 Effect of isopropanolrinse and top layer coating deposition on resist layer thickness (afterintermediate soft bake of Photoresist Layer) Thickness Thickness of FilmInitial Composition of After IPA from IPA Coating Coating Thickness IPASolution Solution Solution 1 XP-1020A 2430 Å IPA only 2428 Å  −2 Å   2XP-1020A 2775 Å Example 1/IPA 3550 Å 774 Å

TABLE 3 Effect of isopropanol rinse and top layer coating deposition onresist layer thickness (without intermediate soft bake of PhotoresistLayer) Final Thickness Thickness of Film Initial Composition of Afterfrom IPA Coating Coating Thickness IPA Solution Coating Solution 3XP-1020A 2963 Å IPA only 2938 Å  −25 Å   4 XP-1020A 2967 Å Example 1/IPA3609 Å 635 ÅStack Formation

To measure barrier performance, wafers were coated with a 60 nm thick acommercially available organic antireflective layer cured at 215° C. andthen coated a methacrylate based 193 nm photoresist. The resist was thenoptionally soft baked prior to deposition of top coat layer. Isopropanolwas optionally applied to the wafers to prewet and rinse the surface ofthe resist prior to the deposition of the top coat. After deposition ofthe top coat layer the films were soft baked at a temperature of 90 or120° C. for 1 minute.

EXAMPLE 8 Barrier Composition Layer Performance

The stack wafers were either left unexposed or exposed to 193 nmradiation. Next the wafers were all soft baked at 120° C. for 1 minute,the standard post exposure bake temperature for the methacrylate basedresist. A 1 mL de-ionized water droplet was then placed in contact withthe wafer in a restricted area using a PTFE o-ring for a period of 60seconds. The droplet was then removed and analyzed by LC/mass spec forthe photoacid in the resist and its photo-degradation byproducts todetermine the efficacy of the prewet prerinse and top coat layermaterials to reduce the contamination in the water phase (immersionfluid). TABLE 4 Barrier Performance as a Function of Top LayerComposition and Prewet/Rinse Step Top Layer IPA Prewet Water PrerinsePre Exposure Post Exposure None No no 17.9 31.4 None yes no 5.9 13.2None No yes 1.4 11.5 Example 1 No no 2.2 10.0 Example 1 No yes 1.0 4.0None No no 17.1 35.6 Example 2 No no 2.7 4.3 Example 3 No no 29.7 53.9Example 4 No no 13.8 40.7 Example 5 No no 2.4 9.2 Example 6 No no 0.92.2

EXAMPLE 9 Lithographic Processing

The following lithographic results (set forth in Table 5 below) wereobtained upon patterned exposure (193 nm) of the photoresist withspecified barrier composition layers (i.e. barrier composition layers ofExample 1 and 6). TABLE 5 Exposure Results using an ArF High NA Step andScan Tool Resist + Resist + Barrier Barrier Layer Layer Property Resist(Example 1) (Example 6) Unit Depth of Focus at 0.45 0.42 — micrometer10% Exposure LER at nominal 7.0 7.2 7.3 nanometer focus and exposure

EXAMPLE 10 Optical Properties of Barrier Composition Layer Opticalproperties of barrier compositions were evaluated at 193 nm and 248 nm.Results are set forth in Table 6 below.

TABLE 6 Optical properties of barrier composition layers OpticalProperty Wavelength n k n k 193 nm 193 nm 248 nm 248 nm Example 1 1.5920.0022 1.511 0.0000 Example 6 1.543 0.0005 1.479 0.0000

1. A method for processing a photoresist composition, comprising: (a)applying on a substrate a photoresist composition; (b) applying abovethe photoresist composition a barrier composition that comprises one ormore components other than resin having fluorinated backbonesubstitution; (c) immersion exposing the photoresist layer to radiationactivating for the photoresist composition.
 2. The method of claim 1wherein the barrier composition comprises one or more resins thatcomprise Si atoms.
 3. A method for processing a photoresist composition,comprising: (a) applying on a substrate a photoresist composition; (b)applying above the photoresist composition an organic barriercomposition layer; (c) in a single step, thermally treating the appliedphotoresist composition and barrier layer composition to remove solventfrom the applied photoresist composition and barrier layer composition;and (d) immersion exposing the photoresist layer to activatingradiation.
 4. The method of claim 3 wherein solvent of the photoresistcomposition is not removed by thermal treatment prior to applying thebarrier layer composition.
 5. A method for processing a photoresistcomposition, comprising: (a) applying on a substrate a photoresistcomposition; (b) treating the applied photoresist composition with afluid composition; and (c) immersion exposing the photoresist layer toradiation activating for the photoresist composition.
 6. The method ofclaim 5 wherein a barier composition is applied above the treatedphotoresist composition layer.
 7. The method of claim 5 wherein thephotoresist composition is treated with an aqueous fluid composition. 8.The method of claim 5 wherein the photoresist composition is treatmentwith a fluid composition that comprises one or more organic solvents. 9.A coated substrate system comprising: a substrate having thereon: 1) acoating layer of a photoresist composition; and 2) a coating layer of abarrier composition above the photoresist composition layer, the barriercomposition comprising one or more non-fluorinated components; and 3) animmersion photolithography exposure tool.
 10. An organic barrier coatingcomposition adapted for use with an underlying photoresist compositionin an immersion photolithography process, the barrier coatingcomposition comprising one or more silsesquioxane resins and one or morefluorinated organic resins.